java多线程网页下载代码

Tue, 15 Nov 2011 00:00:00 +0000

小项目，练手的。

1.使用了java.util.concurrent包里的线程池，可以飙升到满带宽，在100M带宽上，可以达到10MB/s。

2.使用了java.nio里的channels，性能比自己缓冲有一些提高。

import java.io.FileOutputStream;
import java.io.InputStream;
import java.net.URL;
import java.net.URLConnection;
import java.nio.channels.Channels;
import java.nio.channels.FileChannel;
import java.nio.channels.ReadableByteChannel;
import java.util.Calendar;
import java.util.concurrent.Callable;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;

public class HttpDownloader implements Callable {
 URLConnection connection;
 FileChannel outputChann;
 public static volatile int count = 0;

 public static void main(String[] args) throws Exception {

 ExecutorService poll = Executors.newFixedThreadPool(100);

 for (int i = 0; i &lt; 100; i++) {
 Calendar now = Calendar.getInstance();
 String fileName = "../data/" + now.get(Calendar.YEAR) + "年"
 + (now.get(Calendar.MONTH) + 1) + "月"
 + now.get(Calendar.DAY_OF_MONTH) + "日--" + i + ".txt";
 poll.submit(new HttpDownloader("http://www.sina.com",
 (new FileOutputStream(fileName)).getChannel()));
 }

 poll.shutdown();

 long start = System.currentTimeMillis();
 while (!poll.isTerminated()) {
 Thread.sleep(1000);
 System.out.println("已运行"
 + ((System.currentTimeMillis() - start) / 1000) + "秒，"
 + HttpDownloader.count + "个任务还在运行");
 }
 }

 public HttpDownloader(String url, FileChannel fileChannel) throws Exception {
 synchronized (HttpDownloader.class) {
 count++;
 }
 connection = (new URL(url)).openConnection();
 this.outputChann = fileChannel;
 }

 @Override
 public String call() throws Exception {
 connection.connect();
 InputStream inputStream = connection.getInputStream();
 ReadableByteChannel rChannel = Channels.newChannel(inputStream);
 outputChann.transferFrom(rChannel, 0, Integer.MAX_VALUE);
 // System.out.println(Thread.currentThread().getName() + " completed!");
 inputStream.close();
 outputChann.close();
 synchronized (HttpDownloader.class) {
 count--;
 }
 return null;
 }
}

jdbc使用DataSource连接mysql,postgresql,oracle的代码

Tue, 15 Nov 2011 00:00:00 +0000

import java.sql.Connection;
import java.sql.ResultSet;
import java.sql.ResultSetMetaData;
import java.sql.SQLException;
import java.sql.Statement;

import org.postgresql.ds.PGSimpleDataSource;

import oracle.jdbc.pool.OracleDataSource;

import com.mysql.jdbc.jdbc2.optional.MysqlDataSource;

public class DBConnection {

 /**
 * @param args
 * @throws SQLException
 */
 public static void main(String[] args) throws SQLException {
 // TODO Auto-generated method stub
 MysqlDataSource mysqlDataSource = new MysqlDataSource();
 // mysqlDataSource.setPassword("dev");
 // mysqlDataSource.setUser("dev");
 mysqlDataSource
 .setURL("jdbc:mysql://localhost/forJava?user=dev&#038;password=dev");
 Connection conn = mysqlDataSource.getConnection();
 Statement stmt = conn.createStatement();
 stmt.executeUpdate("create table if not exists web\n" + "(\n"
 + " id int not null primary key,\n" + " name varchar(100),\n"
 + " created timestamp,\n" + " content blob\n" + ");\n" + "");
 for (int i = 0; i &lt; 1; i++) {
 stmt.executeUpdate("insert into web (name,content) values ('HL','frgertrhrtnthtohioh')");
 }
 showResultSet(stmt.executeQuery("select * from web limit 10"));

 // Driver driver = new com.mysql.jdbc.Driver();
 // driver.connect("jdbc:mysql://localhost/forJava?user=dev&#038;password=dev",
 // null);

 PGSimpleDataSource pgSimpleDataSource = new PGSimpleDataSource();
 pgSimpleDataSource.setServerName("localhost");
 pgSimpleDataSource.setDatabaseName("dev");
 pgSimpleDataSource.setUser("dev");
 pgSimpleDataSource.setPassword("dev");
 conn = pgSimpleDataSource.getConnection();
 // conn =
 // DriverManager.getConnection("jdbc:postgresql://localhost/test",
 // "dev", "dev");
 showResultSet(conn.createStatement().executeQuery("select * from cities"));

 OracleDataSource oraDataSource = new OracleDataSource();
 // oraDataSource.setServerName("127.0.0.1");
 // oraDataSource.setDatabaseName("HR");
 // oraDataSource.setUser("HR");
 // oraDataSource.setPassword("HR");
 oraDataSource.setURL("jdbc:oracle:thin:hr/hr@//localhost:1521/XE");
 conn = oraDataSource.getConnection();
 stmt = conn.createStatement();
 stmt.execute("select * from tab");
 showResultSet(stmt.getResultSet());
 stmt.execute("select * from jobs");
 showResultSet(stmt.getResultSet());
 stmt.execute("select * from DEPARTMENTS");
 showResultSet(stmt.getResultSet());
 }

 static void showResultSet(ResultSet resultSet) throws SQLException {
 ResultSetMetaData resultSetMetaData = resultSet.getMetaData();
 int num = resultSetMetaData.getColumnCount();
 while (resultSet.next()) {
 for (int i = 1; i &lt;= num; i++) {
 System.out.print(resultSetMetaData.getCatalogName(i) + " "
 + resultSet.getString(i));
 }
 System.out.println();
 }
 }
}

呃，在自己电脑上同时安装了mysql, postgresql,oracle,db2,sqlite的人是不是很蛋疼？

Java on Tech Explorer

java多线程网页下载代码

jdbc使用DataSource连接mysql,postgresql,oracle的代码